The present invention relates to a boom arrangement and more specifically to a method and apparatus for increasing the overall effective length of a boom assembly.
During operation of a boom assembly it is frequently desirable to increase the overall effective length of the boom assembly. To accomplish this, boom extension sections have previously been utilized. The boom extension sections have previously been stored alongside a main boom assembly to enable the relatively rugged main boom assembly to be used to lift heavy loads when the increased length is not required and to facilitate over-the-road transportation. Various arrangements for increasing the overall length of a boom assembly by using one or more boom extension sections are disclosed in U.S. Pat. Nos. 3,125,227; 3,366,250; 3,698,569; 3,732,988; 3,785,505; 3,831,771; 3,885,677; 3,944,082 and 3,968,884. In addition to the disclosures in the aforementioned patents, it has been suggested that a pair of boom extension sections could be mounted beside the base section of a main boom assembly.
Whenever the effective length of a main boom assembly is to be increased by the use of boom extension sections, it is necessary to move the boom extension sections from their storage positions to operating positions in which they extend outwardly from the main boom assembly. In order to facilitate movement of one boom extension section from the storage position to its operating position, it has been suggested that the inner end of the one boom extension section be pivotally connected with the outer end of the boom assembly and swung into position in a manner shown in the aforementioned patents. However, when the effective length of a boom assembly is to be increased by the use of a pair of boom extension sections, difficulty has been encountered in positioning the second or outer one of the two boom extension sections.